In conventional polymer wet spinning procedures, these problems always become evident when large quantities of additives are admixed in a finely dispersed manner, and the obtained solutions are to be processed via spinning. In particular, highly acidic and alkaline working conditions of the kind necessary for dissolving and regenerating the cellulose greatly limit the number of possible additives. In addition, it is known that larger quantities of additives can result in a loss of spinability, e.g., due to viscosity changes in both melt spinning processes and conventional wet spinning procedures.
While these disadvantages are circumvented by using the Lyocell procedure (DE 44 26 966 A1), the procedure in the described form does not enable the manufacture of multiple-layer, functional threads.